Non-corrosive fuels



United States Patent Q NON-CORROSIVE FUELS Joseph E. Fields and GeorgeW. Zopf, Jr., Dayton, Ohio, assignors to Monsanto Chemical Company, St.Louis, Mo., a corporation of Delaware N Drawing. Application November19, 1956 Serial No. 622,756

2 Claims. (Cl. 44-77) This invention relates to non-corrosive fuel oilsand deals more particularly with liquid petroleum distillate fuels whichhave been rendered non-corrosive and to methods of inhibiting rustformation by said liquids under static and dynamic conditions.

Corrosion of metal tanks in which hydrocarbon fuels, i.e., kerosene andgasoline, are stored frequently occurs owing to the presence of tracesof moisture therein, e.g., as a result of refinery practices or due tothe condensation of moisture-laden air in partially filled tanks. Metalpipelines through which the fuels are transported often have a film ofWater droplets upon the inside Walls thereof as a result of temperaturechanges which are conducive to separation of dissolved water. Inaviation gasoline water may appear in a separate phase by entrainmentfrom fueling pumps or as the result of moisture condeusation in the fueltank at high altitude temperatures. Acidic additives, traces of refineryacid, or small quantities of acidic combustion products may also beresponsible for corrosion of metals in petroleum fuel systems.

Corrosion of fuel-handling equipment poses problems of considerablemagnitude. Internal rust and corrosion of pipelines produces two adverseeffects: products are contaminated with rust Particles and pipelinecapacity is progressively reduced. Besides indicating loss of metal, therust particles which are formed and suspended in the fuel are highlyabrasive; hence there ensues erosion of pumps, valves, meters and otherexpensive equipment. Frequent overhaul of line meters is necessitated.

In storage systems including pipeline terminal tanks, bulk storage tanksand service station and consumer tanks, corrosion of the metalliccontainers results not only in deterioration of these storage facilitiesbut also in contamination of the fuel.

In oil tankers, the clean-service life of cargo tanks and tankers isoften reduced as much as 50 percent owing to tanker hold corrosion.

Rust in motor fuels is of concern to both automotive and aviationindustries in that the suspended rust particles are extremely damagingto carburetors and fuel pumps. Rust particles not trapped by fuelfilters often contribute to engine Wear because these particles aregenerally unaffected by combustion.

Accordingly, an object of the invention is to protect liquid petroleumfuel handling facilities against corrosion. Another object is theprevention of rust deposition in sa d fuel when stored in heavy metal,e.g., iron, steel, brass, copper or zinc containers, or transferred inmetal pipelines. Still another object of the invention is the preventionof eroding suspensions of rust in petroleum hydrocarbon fuels.

These and other objects hereinafter disclosed are provided by thefollowing invention wherein there is incorporated with the fuel a smallamount, say from 0.0001 percent to a 0.01 percent of a dimericmono-alkyl ketene having from 8 to 18 carbon atoms in the alkyl radical,e.g., n-octyl ketene dimer, Z-ethylhexyl ketene dimer,

isononyl ketene dimer, n-decyl ketene dimer, n-hendecyl ketene dimer,Z-butyloctyl ketene dimer, tert-dodecyl ketene dimer, n-tetradecylketene dimer, 7-ethyl-2-rnethyl hendecyl ketene dimer, n-tetradecylketene dimer, nhexadecyl ketene dimer, n-heptadecyl ketene dimer,noctadecyi ketene dimer, etc. he presently useful alkyl ketene dimersare known compounds which are obtainable, e.g., by thedehydrohalogenation of acid halides.

The following specific examples illustrate the effectiveness of thepresently disclosed mono-alkyl ketene dimer as a corrosion preventativein gasoline.

Example 1 This example describes evaluation of the rust-inhibitingproperties of a hexadecyl ketene dimer supplied by Hercules iowderCompany and reported by the supplier to possess the followingcharacteristics:

Apparent molecular weight: About 530 Physical form: Flaked solid Color:Almost white Melting point: 110 F.

Bulk density: About 25 pounds per cubic foot in flaked form.

3 X /4" 1; 20 gauge low carbon cold rolled steel specimens which hadbeen cleaned with gasoline, sand blasted to a fresh uniform surface,boiled in methanol and stored in a desiccator were placed in clean 4-02.bottles containing ml. of gasoline into which had been incorporatedvarying amounts of hexadecyl ketene dimer, respectively. Each of thebottles was shaken moderately for 3 minutes and allowed to stand for 30minutes. To each bottle there was then added 3 ml. of water and theresulting mixtures were shaken for 3 minutes. The bottles with theircontents were allowed to stand for 24 hours at room temperature and therespective specimens were then removed therefrom. After washing themwith gasoline and acetone they were examined under a 100- watt daylightbulb for rust dots and/or rusted areas. Specimens which had thus beenimmersed in the presence of either 10 p.p.m., 30 p.p.m., or 100 p.p.m.,of the hexadecyl ketene dimer were completely clean, no evidence ofrusting being present.

Example 2 This example describes evaluation of the water tolerance ofisooctane containing hexadecyl ketene dimer as a rust inhibitor. To ml.of the isooctane containing an 0.008% concentration of said dimer therewas added ml. of distilled water at room temperature. The whole was thenshaken vigorously for 2 minutes without swirling and then allowed tostand on a vibration-free surface for 5 minutes. Observation of the testsample at the end of that time showed that the isooctane had separatedsharply from the water layer and that there was no evidence of anemulsion, precipitate, or suspended material within or present with theisooctane or the water layer. No change in the volume of either layerwas observed.

T results in Examples 1 and 2 above clearly demonstrate that hexadecylketene dimer is a very effective inhibitor of corrosion whenincorporated into gasoline and that its use in fuels containing waterdoes not lead to any problems of emulsifying or decomposition.

instead of employing hexadecyl ketene dimer in the production of thepresent non-corrosive hydrocarbon fuels there may be employed otheralkyl ketene dimers or mixtures of such dimers in varying proportionse.g., dodecyl ketene dimer, a mixture of n-octyl and 2-ethylhexyl ketenedimer, tetradecyl ketene dimer, octadecyl ketene dimer, etc. The dimersare effective metal'corrosion incarbonfu'els generally, and areespecially valuable when used with light gasoline fractions andparticularly with fuels having a high octane rating e.g., those intendedfor use'in'e'ngines' of high compressor efiiciency. The present rustinhibitors'are efiective in motor gradegasol'mes in which the presenceof water is merely incidental as well as in 'jet fuels in which waterand methanol may be customarily employed components. 7

"Addition of the present alkyl ketene dimers to the fuel stock may beeifected in several ways, but most con veniently :the dimer is added tothe stock at the time of blending with other additives, e.g., anti knockadditives such as tetraethyl lead, the anti-foam additives such as thesilicones, etc. The present dimers are very stable compounds whichapparently are not affected by, nor

react with, other additives generally employed in the preparation offuel blends. When employing the dimers as anti-corrosive agents inpipelines the dimer may be added as desired at various points of thesystem, but because the alkyl ketene dimers are effective in very smallconcentrations and because they are not adversely affected by Water itis more convenient to incorporate the dimer into the fuels only as theyenter the system, for example by means of a proportioning pump.'

What we claim is: I I a l. A non-corrosive fuel consisting essentiallyof a normally liquid petroleum distillate containing acorrosion-inhibiting amount of a dimeric mono-alkyl ketene having from 8to 18 carbon atoms in the alkyl radical.

2. A non-corrosive fuel consisting essentially of a normally liquidpetroleum distillate containing, a'corrosion-inhibiting amount ofhexadecyl kete ne dimer.

References Cited in the file of this patent UNITED STATES PATENTS2,430,058 Klaber Nov. 4, 1947 2,627,477 Downey Feb. 3, 1953 OTHERREFERENCES 7 Chemical Trade Names and Commercial Synonyms,

Haynes, Second Ed., October 1955, Van Nostrand Co., N.Y., p. 72. a

1. A NON-CORROSIVE FUEL CONSISTING ESSENTIALLY OF A NORMALLY LIQUIDPETROLEUM DISTILLATE CONTAINING A CORRISION-INHIBITING AMOUNT OF ADIMERIC MONO-ALKYL KETENE HAVING FROM 8 TO 18 CARBON ATOMS IN THE ALKYLRADICAL.